Temporary works training course study Pack - Book - Page 110
Case Study 1
The Loddon Bridge Disaster, Berkshire, October 1972
The collapse
In August 1972 the falsework that had supported the westbound carriageway deck pour was
moved over to the eastbound carriageway. The two structures were separated by a gap of just
2 feet 10 inches (0.86 m). The falsework was dragged across on a temporary track. It was
inspected and some defects were rectified before it was put into use. Some questions were
raised as to whether the falsework was truly plumb but works proceeded.
The concrete to the eastbound
carriageway deck was poured
on 24 October 1972. It was
estimated that around 750 cubic
yards
(570 m3)
of
concrete
would be required, of which 500
cubic yards (380 m3) was on
top
of
the
River
Loddon
falsework system and the remainder over adjacent spans. Four concrete pumps were provided
and four gangs of workers, 30 men in total, with 14 vibrating pokers were in use. Placement of
concrete began at 8:30 am at a rate of around 84 cubic yards (64 m3) per hour, dropping to
50 cubic yards (38 m3) per hour later that morning before rising again to 88 cubic yards
(67 m3) per hour.
At 1:35 pm the east end of the formwork fell around 6 inches (150 mm). Seconds later the
entire deck plunged into the river below. The trestle towers at the east end of the span
overturned and fell onto the deck, though those at the west end remained standing. Three
workers were killed and 10 injured, 7 of them seriously.
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